Image processing apparatus, image processing method, and image processing system

ABSTRACT

There is provided an image processing apparatus including a processing unit configured to processes projection data in which X-ray detection data representing a detection result of parallel beam X-rays output from an X-ray source has been converted by projection, and form an X-ray image based on the X-ray detection data.

BACKGROUND

The present disclosure relates to an image processing apparatus, animage processing method, and an image processing system.

For example, a CT (computed tomography) apparatus (or a CT system;hereinafter, the same) that utilizes X-rays output from an X-ray sourceor an apparatus (or a system; hereinafter, the same) having atomosynthesis function that utilizes X-rays is widely used in themedical field, for example. JP-A-2004-329784 describes a technologyrelating to a CT apparatus that utilizes X-rays.

SUMMARY

A CT apparatus and the like that utilizes X-rays forms an X-ray image byprocessing X-ray detection data representing a detection result ofX-rays. More specifically, in a CT apparatus and the like that utilizesX-rays, an X-ray image is formed based on X-ray detection data beingconverted into projection data, and three-dimensional data beingreconstituted from the projection data, for example.

Here, in a CT apparatus and the like that utilizes X-rays, an X-raysource that outputs cone beam X-rays is used, or an X-ray source thatoutputs fan beam X-rays like the technology described inJP-A-2004-329784 is used, for example.

However, when forming an X-ray image by processing projection data inwhich X-ray detection data representing a result that X-rays output froman X-ray source that outputs cone beam X-rays or an X-ray source thatoutputs fan beam X-rays have been detected has been converted, mixing ofdata of a plurality of layers of a target that is hit by the X-raysoccurs in the projection data due to widening and unevenness of thedetection intensity resulting from the cone beam or the fan beam, forexample. Further, in order to strictly carry out the reconstitution ofthree-dimensional data from projection data in which data from variouslayers is mixed like this, calculations are performed that repeatedlyuse all of the projection data and all of the reconstitution data.

Therefore, to form an X-ray image having greater accuracy by processingprojection data in which X-ray detection data representing a result thatX-rays output from an X-ray source that outputs cone beam X-rays or anX-ray source that outputs fan beam X-rays have been detected has beenconverted, the calculation costs for forming the X-ray image become verylarge.

Examples of methods for performing the calculations for forming an X-rayimage more rapidly include ignoring the effects caused by a cone beam ora fan beam, or converting a cone beam or a fan beam into a parallel beamin the projection data and dividing the processing for forming the X-rayimage.

However, when using such a method for performing the calculations forforming an X-ray image more rapidly, since approximate processing isincluded when forming the X-ray image, the calculation accuracydeteriorates, so that the accuracy of the obtained X-ray imagedeteriorates.

According to an embodiment of the present disclosure, there are provideda novel and improved image processing apparatus, image processingmethod, and image processing system that can achieve a higher qualityX-ray image while reducing the calculation costs for reconstituting anX-ray image even further.

According to an embodiment of the present disclosure, there is providedan image processing apparatus including a processing unit configured toprocesses projection data in which X-ray detection data representing adetection result of parallel beam X-rays output from an X-ray source hasbeen converted by projection, and form an X-ray image based on the X-raydetection data.

Further, according to an embodiment of the present disclosure, there isprovided an image processing method including processing projection datain which X-ray detection data representing a detection result ofparallel beam X-rays output from an X-ray source has been converted byprojection, and forming an X-ray image based on the X-ray detectiondata.

Further, according to an embodiment of the present disclosure, there isprovided an image processing system including an X-ray output apparatusthat includes an X-ray source for outputting parallel beam X-rays, adetection apparatus configured to detect the parallel beam X-rays,generate X-ray detection data representing a detection result of theparallel beam X-rays, and convert the generated X-ray detection datainto projection data by projection, and an image processing apparatusthat includes a processing unit configured to process projection data inwhich the X-ray detection data has been converted, and form an X-rayimage based on the X-ray detection data.

According to the embodiments of the present disclosure described above,a higher quality X-ray image can be achieved while reducing thecalculation costs for reconstituting an X-ray image even further.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram illustrating a first example of the processingperformed in an image processing method according to an embodiment ofthe present disclosure performed by an image processing apparatusaccording to an embodiment of the present disclosure;

FIG. 2 is a flow diagram illustrating an example of reconstitutionprocessing performed by the image processing apparatus according to anembodiment of the present disclosure;

FIG. 3 is an explanatory diagram illustrating the processing performedin the image processing method according to an embodiment of the presentdisclosure;

FIG. 4 is an explanatory diagram illustrating the processing performedin the image processing method according to an embodiment of the presentdisclosure;

FIG. 5 is an explanatory diagram illustrating the processing performedin the image processing method according to an embodiment of the presentdisclosure;

FIG. 6 is a flow diagram illustrating a second example of the processingperformed in the image processing method according to an embodiment ofthe present disclosure performed by the image processing apparatusaccording to an embodiment of the present disclosure;

FIG. 7 is an explanatory diagram illustrating processing performed inthe image processing method according to an embodiment of the presentdisclosure;

FIG. 8 is a flow diagram illustrating a third example of the processingperformed in the image processing method according to an embodiment ofthe present disclosure performed by the image processing apparatusaccording to an embodiment of the present disclosure;

FIG. 9 is an explanatory diagram illustrating an example of an imageprocessing system according to an embodiment of the present disclosure;

FIG. 10 is a block diagram illustrating an example of a configuration ofthe image processing apparatus according to an embodiment of the presentdisclosure; and

FIG. 11 is a diagram illustrating an example of a hardware configurationof the image processing apparatus according to an embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Further, the description will be made in the following order.

-   1. Image processing method according to the present embodiment-   2. Image processing apparatus according to the present embodiment-   3. Program according to the present embodiment    (Image Processing Method According to the Present Embodiment)

Before describing the configuration of the image processing apparatusaccording to the present embodiment, first, the image processing methodaccording to the present embodiment will be described. In the following,the image processing method according to the present embodiment will bedescribed based on an example in which the image processing apparatusaccording to the present embodiment performs the processing performed inthe image processing method according to the present embodiment.

(1) Outline of the Image Processing Method According to the PresentEmbodiment

As described above, when forming an X-ray image having greater accuracyby processing projection data in which X-ray detection data representinga result that X-rays output from an X-ray source that outputs cone beamX-rays or an X-ray source that outputs fan beam X-rays have beendetected has been converted, the calculation costs for forming the X-rayimage become very large. Further, when using the above-described methodfor performing the calculations for forming an X-ray image more rapidly,since approximate processing is included when forming the X-ray image,the calculation accuracy deteriorates, so that the accuracy of theobtained X-ray image deteriorates.

Accordingly, the image processing apparatus according to the presentembodiment forms an X-ray image based on X-ray detection data byprocessing projection data in which X-ray detection data representing adetection result of parallel beam X-rays output from an X-ray source hasbeen converted.

Here, the X-ray detection data according to the present embodiment is,for example, data representing a detection intensity of parallel beamX-rays that have passed through a target and have been detected by adetector, such as the detector that is included in the below-describeddetection apparatus according to the present embodiment. In thefollowing, to differentiate between the X-ray detection data accordingto the present embodiment and the X-ray detection data representing adetection result of cone beam X-rays or fan beam X-rays, the X-raydetection data according to the present embodiment is sometimes referredto as “parallel X-ray detection data”.

The parallel X-ray detection data representing the detection intensityof the parallel beam X-rays detected by the above-described detector isconverted into projection data (two-dimensional projection data) bybeing projected in two dimensions as an X-ray projection image. Morespecifically, the parallel X-ray detection data is converted intoprojection data by radon conversion, for example.

Here, although the conversion processing for converting the parallelX-ray detection data into projection data is performed by an externaldevice, such as the detection apparatus (described below) according tothe present embodiment, that generates the X-ray detection dataaccording to the present embodiment, for example, the conversionprocessing according to the present embodiment is not limited to beingperformed by an external device. For example, the image processingapparatus according to the present embodiment may perform the conversionprocessing according to the present embodiment. In the following, theprocessing performed in the image processing method according to thepresent embodiment will be described mainly based on an example in whichthe conversion processing according to the present embodiment isperformed by an external device, such as the detection apparatusaccording to the present embodiment, that generates parallel X-raydetection data, namely, a case in which the image processing apparatusaccording to the present embodiment processes projection data in whichthe parallel X-ray detection data has already been converted by theexternal device.

Further, although the image processing apparatus according to thepresent embodiment processes projection data in which parallel X-raydetection data has been converted, or parallel X-ray detection data,acquired from an external device such as the below-described detectionapparatus according to the present embodiment, the projection data inwhich parallel X-ray detection data has been converted or the parallelX-ray detection data processed by the image processing apparatusaccording to the present embodiment is not limited to that describedabove. For example, the image processing apparatus according to thepresent embodiment can also perform the processing by reading from astorage unit (described below) projection data in which parallel X-raydetection data has been converted, or parallel X-ray detection data,that is stored in a storage unit (described below) included in theapparatus (the image processing apparatus according to the presentembodiment) or stored on an external storage medium, for example.

More specifically, the image processing apparatus according to thepresent embodiment forms an X-ray image by reconstitutingthree-dimensional data from the projection data.

Here, examples of the processing used by the image processing apparatusaccording to the present embodiment to reconstitute three-dimensionaldata from the projection data include successive approximation methods,such as ML-EM (maximum likelihood-expectation maximization), OS-EM(ordered subsets-expectation maximization), and MAP-EM (maximum aposteriori-expectation maximization). It is noted that the processingperformed to reconstitute three-dimensional data from the projectiondata according to the present embodiment is obviously not limited toprocessing that uses the successive approximation methods mentionedabove.

In processing using a successive approximation method like thosementioned above, a value close to the correct value is obtained byrepeated projection of a reconstituted image and reverse-projection ofan image (corrected image) in which the reconstituted image has beencorrected. Therefore, the image processing apparatus according to thepresent embodiment can form a highly accurate X-ray image by performingprocessing that uses a successive approximation method like thosementioned above as the processing to reconstitute three-dimensional datafrom projection data.

Therefore, the image processing apparatus according to the presentembodiment can achieve a higher quality X-ray image.

Further, as described above, the image processing apparatus according tothe present embodiment forms an X-ray image based on parallel X-raydetection data by processing projection data in which parallel X-raydetection data has been converted. Here, in the projection data in whichparallel X-ray detection data has been converted, there is no mixing ofthe data of the plurality of layers of the target, as is the case in theabove-described projection data in which X-ray detection datarepresenting a detection result of cone beam or fan beam X-rays has beenconverted. This is because projection data in which parallel X-raydetection data has been converted is not affected by the above-describedwidening and unevenness of the detection intensity resulting from a conebeam or a fan beam.

Therefore, by processing projection data in which parallel X-raydetection data has been converted, the image processing apparatusaccording to the present embodiment does not have to perform processingto reduce the effects of a cone beam or a fan beam, such as geometriccorrection, distortion correction, noise removal and the like.

Accordingly, the image processing apparatus according to the presentembodiment can reduce the calculation costs for forming an X-ray imagemore than when processing the above-described X-ray detection data thatrepresents a detection result of cone beam or fan beam X-rays.

Further, since the image processing apparatus according to the presentembodiment does not have to perform processing to reduce the effects ofa cone beam or a fan beam, such as geometric correction, distortioncorrection, noise removal and the like, approximation or imagedeterioration resulting from processing to reduce the effects of a conebeam or a fan beam is prevented. Therefore, the image processingapparatus according to the present embodiment can achieve a higherquality X-ray image.

In addition, by processing projection data in which parallel X-raydetection data has been converted, since there is no mixing of the dataof the respective layers of the target in the projection data,deterioration in the accuracy of the X-ray image is prevented even ifthe image processing apparatus according to the present embodimentprocesses only the parallel X-ray detection data corresponding to aspecific layer of the target. Namely, by processing projection data inwhich parallel X-ray detection data has been converted, with the imageprocessing apparatus according to the present embodiment it is possibleto process only the parallel X-ray detection data corresponding to aspecific layer of the target.

Therefore, the image processing apparatus according to the presentembodiment is capable of performing processing (e.g., processing fordividing the projection data and forming an X-ray image for each pieceof divided projection data (described below)) in parallel. Further,since the image processing apparatus according to the present embodimentcan form successive X-ray images each time projection data is acquired(described below), for example, the amount of memory that is used in onecalculation is substantially reduced.

(2) Processing Performed in the Image Processing Method According to thePresent Embodiment

Next, the processing performed in the image processing method accordingto the present embodiment will be described in more detail.

In the following, the processing performed in the image processingmethod according to the present embodiment will be described based on anexample in which the image processing apparatus according to the presentembodiment processes projection data in which parallel X-ray detectiondata has been converted by an external device. It is noted that when theimage processing apparatus according to the present embodiment processesparallel X-ray detection data, the image processing apparatus accordingto the present embodiment converts the parallel X-ray detection datainto projection data, for example, and processes the convertedprojection data.

(2-1) First Example of the Processing Performed in the Image ProcessingMethod According to the Present Embodiment

FIG. 1 is a flow diagram illustrating a first example of the processingperformed in an image processing method according to the presentembodiment performed by an image processing apparatus according to thepresent embodiment.

The image processing apparatus according to the present embodimentdetermines whether projection data has been acquired (S100). The imageprocessing apparatus according to the present embodiment determines thatprojection data has been acquired if all of the projection datacorresponding to the target has been read into a RAM (random-accessmemory), for example.

If it is determined in step S100 that projection data has not beenacquired, the image processing apparatus according to the presentembodiment does not proceed to the next processing step until projectiondata is acquired.

Further, if it is determined in step S100 that projection data has beenacquired, the image processing apparatus according to the presentembodiment sets the image represented by the projection data asprojection image P, and sets an initial reconstituted image I₀(S102).

Here, although the image processing apparatus according to the presentembodiment sets the initial reconstituted image I₀ by generating as theinitial reconstituted image I₀ an image in which the pixel values of allof the pixels are positive, such as an image in which the pixel valuesof all of the pixels are indicated as “1”, for example, the processingfor setting the initial reconstituted image I₀ that is performed in thepresent embodiment is not limited to this. For example, in order tocomplete the below-described reconstitution processing more rapidly, theimage processing apparatus according to the present embodiment may setan image reconstituted by a FBP (filtered back-projection) method as theinitial reconstituted image I₀. Further, the image processing apparatusaccording to the present embodiment can also, for example, set anarbitrary image in which the pixel values are positive as the initialreconstituted image I₀.

When the processing of step S102 has been performed, the imageprocessing apparatus according to the present embodiment performsreconstitution processing for forming an X-ray image (S 104).

FIG. 2 is a flow diagram illustrating an example of reconstitutionprocessing performed by the image processing apparatus according to thepresent embodiment.

The image processing apparatus according to the present embodimentprojects a reconstituted image I_(n) (wherein n denotes an integer of 0or more), and generates a reprojection image P′ (S200). Here, thereconstituted image I_(n) that is initially projected by the imageprocessing apparatus according to the present embodiment is the initialreconstituted image I₀ set in step S102 of FIG. 1.

When the processing of step S200 has been performed, the imageprocessing apparatus according to the present embodiment compares thereprojection image P′ and the projection image P, for example, andcalculates a ratio between the reprojection image P′ and the projectionimage P (S202).

When the ratio between the reprojection image P′ and the projectionimage P has been calculated in step S202, the image processing apparatusaccording to the present embodiment determines whether to finish thereconstitution processing (S204). The image processing apparatusaccording to the present embodiment determines that the reconstitutionprocessing is to be finished when, for example, the ratio between thereprojection image P′ and the projection image P calculated in step S202is equal to or less than a predetermined set value (or less than apredetermined value).

If it is not determined in step S204 to finish the reconstitutionprocessing, the image processing apparatus according to the presentembodiment reverse-projects the reprojection image P′ (correction value)using the ratio between the reprojection image P′ and the projectionimage P to generate a new reconstituted image I_(n) (n=n+1) (S206).Then, the image processing apparatus according to the present embodimentrepeats the processing from step S200.

Further, if it is determined in step S204 to finish the reconstitutionprocessing, the image processing apparatus according to the presentembodiment sets the reconstituted image I_(n) as the X-ray image (aso-called reconstituted layer image) (S208). Then, the image processingapparatus according to the present embodiment finishes thereconstitution processing.

The image processing apparatus according to the present embodimentperforms the processing illustrated in FIG. 2, for example, as thereconstitution processing according to the present embodiment.

Here, when the image processing apparatus according to the presentembodiment uses ML-EM, which is a basic successive approximation methodthat uses maximum likelihood estimation, the reconstitution processingaccording to the present embodiment is represented by the followingformula 1, for example.

$\begin{matrix}{\lambda_{j}^{({k + 1})} = {\frac{\lambda_{j}^{(k)}}{\sum\limits_{i = 1}^{n}\; C_{ij}} \cdot {\sum\limits_{i = 1}^{n}\;\frac{y_{i} \cdot C_{ij}}{\sum\limits_{j^{\prime} = 1}^{m}\;{C_{{ij}^{\prime}} \cdot \lambda_{j^{\prime}}^{(k)}}}}}} & ( {{Formula}\mspace{14mu} 1} )\end{matrix}$

The “i” in formula 1 represents the coordinates of the reconstitutedimage (the coordinates corresponding to the position of the target), the“j” in formula 1 represents the coordinates of the projection image P,and the “k” in formula 1 represents the number of repetitions. Further,the “C_(ij)” in formula 1 represents the “detection rate”, which is theprobability of the voxel of coordinate i in the target being detected bya detector corresponding to coordinate j of the projection image P.

Therefore, for example, to reconstitute a given layer by a successiveapproximation method, one calculation cycle can be carried out byplugging all of the voxels of that layer and the values of the detectionpositions corresponding to those voxels. Accordingly, whenreconstituting an X-ray image corresponding to a three-dimensionalobject (target), the reconstituted image and the projection image Pbased on the projection data are three-dimensional, so that thecalculation represented in formula 1 can be carried out on all of thevoxels in three dimensions.

FIG. 3 is an explanatory diagram illustrating the processing performedin the image processing method according to the present embodiment. FIG.3 illustrates an example in a typical CT of the correspondence among theposition of the X-ray source, the position of the target through whichthe X-rays pass, and the position of the detector. Symbol A in FIG. 3illustrates an example in a single-slice type CT apparatus of thecorrespondence among the position of the X-ray source, the position ofthe target through which the X-rays pass, and the position of thedetector. Further, symbol B in FIG. 3 illustrates an example in amulti-slice type CT apparatus of the correspondence among the positionof the X-ray source, the position of the target through which the X-rayspass, and the position of the detector.

For the single-slice type CT apparatus illustrated by A in FIG. 3, sinceone layer and one array of detectors correspond to each other on aone-to-one basis, the successive calculations performed in the abovereconstitution processing can be performed layer by layer. Namely, inthe case of the single-slice type CT apparatus illustrated by A in FIG.3, in formula 1 a two-dimensional×two-dimensional calculation can beperformed. Therefore, when reconstituting the X-ray image using thesingle-slice type CT apparatus illustrated by A in FIG. 3, thecalculation costs to form the X-ray image are smaller than thecalculation costs to form the X-ray image when reconstituting an X-rayimage using the multi-slice type CT apparatus employing an X-ray sourcethat outputs cone beam X-rays like that illustrated by B in FIG. 3.However, with the single-slice type CT apparatus illustrated by A inFIG. 3, the larger the detection area of the target, the longer it takesto generate the X-ray image.

Further, for recent CT apparatuses, in order to increase the detectionarea and shorten the time, a multi-slice type like that illustrated by Bin FIG. 3 is mainstream. Here, for a multi-slice type CT apparatus, anX-ray source that outputs cone beam X-rays is used, as illustrated by Bof FIG. 3.

When an X-ray source that outputs cone beam X-rays is used asillustrated by B of FIG. 3, when an attempt is made to reconstitute theX-ray image corresponding to a given layer, the width of the detectorcorresponding to the X-rays that pass through that layer surfaceincreases. In addition, when the X-ray source and the detector arerotated by a gantry and the like configuring the CT apparatus, theposition of the detector that passes through a given voxel of the targetchanges depending on the angle of rotation.

Therefore, when an X-ray source that outputs cone beam X-rays is used asillustrated by B of FIG. 3, when reconstituting the X-ray imagecorresponding to the layer surface, all of the relevant voxels and thedetectors are used in the calculation. Namely, when reconstituting anX-ray image using an X-ray source that outputs cone beam X-rays asillustrated by B of FIG. 3, all of the voxels and the detectors thathave an effect on each other are used in all the calculations even whentrying to reconstitute the X-ray image corresponding to a given specificlayer surface.

Therefore, when reconstituting an X-ray image using an X-ray source thatoutputs cone beam X-rays as illustrated by B of FIG. 3, the value of allthe voxels in the three-dimensional information about the target and thevalue of all the detectors are used in a given single calculation.Namely, when reconstituting an X-ray image using an X-ray source thatoutputs cone beam X-rays as illustrated by B of FIG. 3, the calculationamount of the detection probability C_(ij) in formula 1 increases.

FIG. 4, which is an explanatory diagram illustrating the processingperformed in the image processing method according to the presentembodiment, illustrates the outline of the processing that is performedwhen reconstituting an X-ray image using a cone beam X-ray source.

As illustrated in FIG. 4, when reconstituting an X-ray image using anX-ray source that outputs cone beam X-rays as illustrated by B of FIG.3, correspondence between three-dimensional data×three-dimensional datais repeatedly calculated based on formula 1. Therefore, whenreconstituting an X-ray image using an X-ray source that outputs conebeam X-rays as illustrated by B of FIG. 3, the calculation amount isvery large. Further, even when reconstituting an X-ray image using a fanbeam X-ray source, similar to when reconstituting an X-ray image usingan X-ray source that outputs cone beam X-rays as illustrated by B ofFIG. 3, the calculation amount relating to the reconstitution of theX-ray image is very large.

Therefore, as described above, when forming an X-ray image havinggreater accuracy by processing projection data in which X-ray detectiondata representing a result that X-rays output from an X-ray source thatoutputs cone beam X-rays or an X-ray source that outputs fan beam X-rayshave been detected has been converted, the calculation costs for formingthe X-ray image become very large.

FIG. 5, which is an explanatory diagram illustrating processingperformed in the image processing method according to the presentembodiment, illustrates an example of a multi-slice type CT apparatus inwhich an X-ray source that outputs parallel beam X-rays is used.

As illustrated in FIG. 5, when an X-ray source that outputs parallelbeam X-rays is used, since X-rays are irradiated from an X-ray sourceparallel to the array of detectors, mixing of the layer data among thelayers is eliminated, so that each cross-section and each detector arrayare independent, and the correspondence between the cross-sections andthe detectors is on a one-to-one basis. Further, as described above, theimage processing apparatus according to the present embodiment forms anX-ray image based on X-ray detection data by processing projection datain which X-ray detection data representing a detection result ofparallel beam X-rays output from an X-ray source has been converted.

Therefore, in the reconstitution processing according to the presentembodiment illustrated in FIG. 2, the image processing apparatusaccording to the present embodiment can perform the successivecalculations for reconstitution on a per layer basis in a closed state.Further, since the reconstitution calculations are alsotwo-dimensional×two-dimensional, the calculation amount that isperformed in one go can be substantially reduced. In addition, thecalculation amount of the detection probability C_(ij) in formula 1 canbe reduced by a lot more than when reconstituting an X-ray image usingan X-ray source that outputs cone beam X-rays as illustrated by B ofFIG. 3, for example.

The image processing apparatus according to the present embodimentperforms the processing illustrated in FIG. 1, for example, as theprocessing performed in the image processing method according to thepresent embodiment.

Here, in the projection data in which parallel X-ray detection data hasbeen converted that is processed by the image processing apparatusaccording to the present embodiment in the processing illustrated inFIG. 1, there is no mixing of data of the plurality of layers of thetarget, as is the case with the above-described projection data in whichX-ray detection data representing a detection result of cone beam or fanbeam X-rays has been converted. Namely, when performing the processingillustrated in FIG. 1, for example, the image processing apparatusaccording to the present embodiment does not have to perform processingto reduce the effects of a cone beam or a fan beam, such as geometriccorrection, distortion correction, noise removal and the like. Further,the calculation amount relating to the reconstitution processingperformed by the image processing apparatus according to the presentembodiment is reduced by a lot more than when processing theabove-described projection data in which X-ray detection datarepresenting a detection result of cone beam or fan beam X-rays has beenconverted. Therefore, when performing the processing illustrated in FIG.1, for example, deterioration resulting from the processing to reducethe effects of a cone beam or a fan beam is prevented. Further, thecalculation costs for forming an X-ray image can be reduced more thanwhen processing the above-described X-ray detection data that representsa detection result of cone beam or fan beam X-rays.

Therefore, by performing the processing illustrated in FIG. 1, forexample, the image processing apparatus according to the presentembodiment can achieve a higher quality X-ray image while reducing thecalculation costs for forming an X-ray image even further.

Further, for example, in the processing illustrated in FIG. 1, the imageprocessing apparatus according to the present embodiment performsprocessing that uses a successive approximation method, such asprocessing using the ML-EM method represented in formula 1, for example,as the reconstitution processing for forming an X-ray image. Therefore,since a highly accurate X-ray image can be formed by performing theprocessing illustrated in FIG. 1, for example, a higher quality X-rayimage can be achieved.

It is noted that the processing performed in the image processing methodaccording to the present embodiment that is performed by the imageprocessing apparatus according to the present embodiment is not limitedto the processing according to the first example illustrated in FIG. 1.

As described above, by processing projection data in which parallelX-ray detection data has been converted, there is no mixing in theprojection data of the data from respective layers in the target.Therefore, a deterioration in the accuracy of the X-ray image isprevented even if the image processing apparatus according to thepresent embodiment processes only the parallel X-ray detection datacorresponding to a specific layer of the target. Namely, by processingprojection data in which parallel X-ray detection data has beenconverted, with the image processing apparatus according to the presentembodiment it is possible to process only the parallel X-ray detectiondata corresponding to a specific layer of the target.

Therefore, the image processing apparatus according to the presentembodiment can, for example, divide the projection data and form anX-ray image for each piece of divided projection data (the parallelprocessing according to the present embodiment). Further, the imageprocessing apparatus according to the present embodiment can also formsuccessive X-ray images each time projection data is acquired (thesuccessive processing according to the present embodiment).

(2-2) Second Example of the Processing Performed in the Image ProcessingMethod According to the Present Embodiment

FIG. 6 is a flow diagram illustrating a second example of the processingperformed in the image processing method according to the presentembodiment by the image processing apparatus according to the presentembodiment. Here, FIG. 6 illustrates an example of the parallelprocessing according to the present embodiment.

Similar to step S100 of FIG. 1, the image processing apparatus accordingto the present embodiment determines whether projection data has beenacquired (S300). If it is determined in step S300 that projection datahas not been acquired, the image processing apparatus according to thepresent embodiment does not proceed to the next processing step untilprojection data is acquired.

Further, if it is determined in step S300 that projection data has beenacquired, the image processing apparatus according to the presentembodiment divides the projection data (S302). Here although the imageprocessing apparatus according to the present embodiment divides theprojection data on a per layer basis, for example, the units that theimage processing apparatus according to the present embodiment dividesthe projection data into are not especially limited. Further, the unitsinto which the image processing apparatus according to the presentembodiment divides the projection data may be, for example, a singleunit, or a mixture of a plurality of units. The image processingapparatus according to the present embodiment sets an image representedby each piece of divided projection data as the projection image P.

Further, if it is determined in step S300 that projection data has beenacquired, the image processing apparatus according to the presentembodiment sets an initial reconstituted image I₀ corresponding to eachpiece of divided projection data (S304). Here, the image processingapparatus according to the present embodiment sets the initialreconstituted image I₀ in the same manner as in step S102 of FIG. 1.

It is noted that although in FIG. 6 an example is illustrated in whichthe processing of step S304 is carried out after the processing stepS302, the processing of step S302 and the processing step S304 can beperformed independently. Therefore, the image processing apparatusaccording to the present embodiment can perform the processing of stepS302 and the processing step S304 in synchronization, for example.

When the processing steps S302 and S304 has been performed, the imageprocessing apparatus according to the present embodiment performs inparallel the reconstitution processing for forming an X-ray image foreach piece of divided projection data (S306). Here, the image processingapparatus according to the present embodiment performs thereconstitution processing for forming X-ray images in the same manner asin step S104 of FIG. 1, for example.

The image processing apparatus according to the present embodimentperforms the processing illustrated in FIG. 6, for example, as theprocessing performed in the image processing method according to thepresent embodiment.

Here, in the projection data that is processed by the image processingapparatus according to the present embodiment in the processingillustrated in FIG. 6, similar to the processing according to the firstexample illustrated in FIG. 1, there is no mixing of data of theplurality of layers of the target. Namely, similar to the processingaccording to the first example illustrated in FIG. 1, when performingthe processing illustrated in FIG. 6, for example, the image processingapparatus according to the present embodiment does not have to performprocessing to reduce the effects of a cone beam or a fan beam, such asgeometric correction, distortion correction, noise removal and the like.Further, similar to the processing according to the first exampleillustrated in FIG. 1, the calculation amount relating to thereconstitution processing performed by the image processing apparatusaccording to the present embodiment is reduced by a lot more than whenprocessing the above-described projection data in which X-ray detectiondata representing a detection result of cone beam or fan beam X-rays hasbeen converted.

Therefore, similar to the processing according to the first exampleillustrated in FIG. 1, by performing the processing illustrated in FIG.6, for example, the image processing apparatus according to the presentembodiment can achieve a higher quality X-ray image while reducing thecalculation costs for forming an X-ray image even further.

Further, in the processing illustrated in FIG. 6, the dividing of theprojection data into respective layers and the reconstitution processingcorresponding to each piece of projection data are performed inparallel.

Therefore, the image processing apparatus according to the presentembodiment can shorten the processing time (calculation time) taken forthe reconstitution processing more than when an X-ray image isreconstituted using an X-ray source that outputs cone beam or fan beamX-rays, for example. In addition, similar to the processing according tothe first example illustrated in FIG. 1, since there is no mixing of thedata of the plurality of layers of the target in the projection dataprocessed by the image processing apparatus according to the presentembodiment, deterioration in the accuracy of the X-ray image isprevented even if the image processing apparatus according to thepresent embodiment processes only the parallel X-ray detection datacorresponding to a specific layer of the target.

(2-3) Third Example of the Processing Performed in the Image ProcessingMethod According to the Present Embodiment

FIG. 7 is an explanatory diagram illustrating the processing performedin the image processing method according to the present embodiment. FIG.7 illustrates an example in a helical scanning type CT apparatus, or ina non-helical scanning type CT apparatus, for example, of thecorrespondence among the position of the X-ray source, the position ofthe target through which the X-rays pass, and the position of thedetector. Further, a person is shown in FIG. 7 as the target.

In a helical scanning type CT apparatus or a non-helical scanning typeCT apparatus like that illustrated in FIG. 7, when an X-ray source thatoutputs cone beam X-rays is used as illustrated by B of FIG. 3,reconstitution processing like that illustrated in FIG. 2 is notperformed until all of the scans of the target are finished. This isbecause, as described above, when reconstituting an X-ray image using anX-ray source that outputs cone beam X-rays, all of the voxels and thedetectors that have an effect on each other are used in all thecalculations even when trying to reconstitute the X-ray imagecorresponding to a given specific layer surface.

In contrast, in the projection data in which parallel X-ray detectiondata has been converted that is processed by the image processingapparatus according to the present embodiment, there is no mixing ofdata of the plurality of layers of the target, as is the case with theabove-described projection data in which X-ray detection datarepresenting a detection result of cone beam or fan beam X-rays has beenconverted. Therefore, as described above, a deterioration in theaccuracy of the X-ray image is prevented even if the image processingapparatus according to the present embodiment processes only theparallel X-ray detection data corresponding to a specific layer of thetarget. Namely, a deterioration in the accuracy of the X-ray image to beformed does not occur even if successive X-ray images are formed eachtime projection data is acquired, for example.

Accordingly, as the processing according to the third example of theimage processing method according to the present embodiment, an examplewill be described of processing that can realize the successiveprocessing according to the present embodiment.

FIG. 8 is a flow diagram illustrating a third example of the processingperformed in the image processing method according to the presentembodiment performed by the image processing apparatus according topresent embodiment. Here, FIG. 8 illustrates an example of thesuccessive processing according to the present embodiment.

The image processing apparatus according to the present embodimentdetermines whether projection data has been acquired (S400). The imageprocessing apparatus according to the present embodiment determines thatprojection data has been acquired if projection data transmitted from anexternal device has been received, and the received projection data readinto the RAM or the like, or if projection data stored in a storage unit(described below) has been read from the storage unit (described below),and the read projection data read into the RAM or the like, for example.

If it is determined in step S400 that projection data has not beenacquired, the image processing apparatus according to the presentembodiment does not proceed to the next processing step until projectiondata is acquired.

Further, if it is determined in step S400 that projection data has beenacquired, the image processing apparatus according to the presentembodiment sets an initial reconstituted image I₀ in the same manner asin step S102 of FIG. 1 (S402).

When the processing step S402 has been performed, the image processingapparatus according to the present embodiment performs thereconstitution processing for forming an X-ray image in the same manneras in step S104 of FIG. 1 (S404).

When the processing step S404 has been performed, the image processingapparatus according to the present embodiment determines whether tofinish the processing performed in the image processing method accordingto the present embodiment (S406). Here, when processing projection databased on parallel X-ray detection data representing a detection resultin a helical scanning type CT apparatus or a non-helical scanning typeCT apparatus like that illustrated in FIG. 7, the image processingapparatus according to the present embodiment determines, for example,to finish the processing performed in the image processing methodaccording to the present embodiment when a signal indicating thatscanning has finished transmitted from an external device, such as theCT apparatus, is received. Further, if projection data stored in astorage unit (described below) or the like is processed, the imageprocessing apparatus according to the present embodiment determines tofinish the processing performed in the image processing method accordingto the present embodiment when, for example, all of projection data(e.g., projection data formed into groups based on metadata and thelike) corresponding to a given target has been read from the storageunit (described below).

If it is not determined in step S406 to finish the processing performedin the image processing method according to the present embodiment, theimage processing apparatus according to the present embodiment repeatsthe processing from step S400. Further, if it is determined in step S406to finish the processing performed in the image processing methodaccording to the present embodiment, the image processing apparatusaccording to the present embodiment finishes the processing performed inthe image processing method according to the present embodiment.

The image processing apparatus according to the present embodimentperforms the processing illustrated in FIG. 8, for example, as theprocessing performed in the image processing method according to thepresent embodiment.

Here, in the projection data that is processed by the image processingapparatus according to the present embodiment in the processingillustrated in FIG. 8, similar to the processing according to the firstexample illustrated in FIG. 1, there is no mixing of data of theplurality of layers of the target. Namely, similar to the processingaccording to the first example illustrated in FIG. 1, when performingthe processing illustrated in FIG. 8, for example, the image processingapparatus according to the present embodiment does not have to performprocessing to reduce the effects of a cone beam or a fan beam, such asgeometric correction, distortion correction, noise removal and the like.Further, similar to the processing according to the first exampleillustrated in FIG. 1, the calculation amount relating to thereconstitution processing performed by the image processing apparatusaccording to the present embodiment is reduced by a lot more than whenprocessing the above-described projection data in which X-ray detectiondata representing a detection result of cone beam or fan beam X-rays hasbeen converted.

Therefore, similar to the processing according to the first exampleillustrated in FIG. 1, by performing the processing illustrated in FIG.8, for example, the image processing apparatus according to the presentembodiment can achieve a higher quality X-ray image while reducing thecalculation costs for forming an X-ray image even further.

In addition, similar to the processing according to the first exampleillustrated in FIG. 1, since there is no mixing of the data of theplurality of layers of the target in the projection data processed bythe image processing apparatus according to the present embodiment,deterioration in the accuracy of the X-ray image is prevented even ifonly the parallel X-ray detection data corresponding to a specific layerof the target is processed. Namely, since the image processing apparatusaccording to the present embodiment can independently perform processingon each layer surface, in the processing illustrated in FIG. 8, theimage processing apparatus according to the present embodiment formssuccessive X-ray images each time projection data is acquired.

Therefore, in a helical scanning type CT apparatus or a non-helicalscanning type CT apparatus like that illustrated in FIG. 7, the imageprocessing apparatus according to the present embodiment perform thecalculations relating to the formation of the X-ray image, such as areconstitution calculation, in order from the portions for whichscanning has finished. For example, the calculations relating to theformation of the X-ray image can be completed along with as thefinishing of the CT scanning.

Further, since the image processing apparatus according to the presentembodiment forms successive X-ray images each time projection data isacquired, the amount of memory that is used in one calculation issubstantially reduced.

(Image Processing Apparatus According to the Present Embodiment)

Next, an example of the configuration of an image processing apparatusaccording to the present embodiment that is capable of performing theprocessing performed in the above-described image processing methodaccording to the present embodiment will be described.

(I) Example of the Configuration of the Image Processing SystemAccording to the Present Embodiment

Before describing an example of the configuration of the imageprocessing apparatus according to the present embodiment, an example ofthe image processing system according to the present embodiment that hasthe image processing apparatus according to the present embodiment willbe described. FIG. 9 is an explanatory diagram illustrating an exampleof an image processing system 1000 according to the present embodiment.The image processing system 1000 has, for example, an image processingapparatus 100, an X-ray output apparatus 200, and a detection apparatus300.

The X-ray output apparatus 200 includes, for example, an X-ray source(not illustrated), for outputting parallel beam X-rays. Here, examplesof the X-ray source included in the X-ray output apparatus 200 includean X-ray tube, which is an electron tube for generating X-rays, acolimeter that forms parallel beam X-rays from X-rays generated by anX-ray tube, and a planar source in which a plurality of X-ray tubes arearranged on a flat face.

It is noted that the configuration of the X-ray output apparatus 200 isnot limited to that described above. For example, the X-ray outputapparatus 200 is configured from a MPU (micro-processing unit), variousprocessing circuits and the like. Further, the X-ray output apparatus200 may also include a control unit (not illustrated) for controllingthe generation of X-rays by the X-ray source, a ROM (read-only memory,not illustrated), a RAM (not illustrated) and the like.

Here, the ROM (not illustrated) included in the X-ray output apparatus200 stores control data, such as programs and calculation parametersused by the control unit (not illustrated) included in the detectionapparatus 300. The RAM included in the X-ray output apparatus 200temporarily stores programs, for example, that are executed by thecontrol unit (not illustrated) included in the X-ray output apparatus200.

The detection apparatus 300, which includes a detection unit (notillustrated) that has a detector for detecting X-rays, for example,detects parallel beam X-rays and generates parallel X-ray detectiondata.

It is noted that the configuration of the detection apparatus 300 is notlimited to that described above. For example, the detection apparatus300 is configured from a MPU, various processing circuits and the like.Further, the detection apparatus 300 may also include a processing unit(not illustrated) for converting parallel X-ray detection data intoprojection data, a ROM (read-only memory, not illustrated), a RAM (notillustrated), a communication unit and the like.

Here, the ROM (not illustrated) included in the detection apparatus 300stores control data, such as programs and calculation parameters used bythe control unit (not illustrated) included in the detection apparatus300. The RAM included in the detection apparatus 300 temporarily storesprograms, for example, that are executed by the control unit (notillustrated) included in the detection apparatus 300.

The communication unit (not illustrated) included in the detectionapparatus 300 is a communication device included in the detectionapparatus 300, which has the role of performing wireless/wiredcommunication with an external device, such as the image processingapparatus 100, via a network (or directly). Here, examples of thecommunication unit (not illustrated) included in the detection apparatus300 include a communication antenna and an RF (radio frequency) circuit(wireless communication), an IEEE 802.15.1 port and atransmitting/receiving circuit (wireless communication), an IEEE 802.11bport and a transmitting/receiving circuit (wireless communication), or aLAN (local area network) terminal and a transmitting/receiving circuit(wired communication) and the like. Further examples of thecommunication unit (not illustrated) included in the detection apparatus300 include a configuration that supports an arbitrary standard capableof performing communication, such as a USB (universal serial bus)terminal and a transmitting/receiving circuit, and an arbitraryconfiguration capable of communicating with an external device via anetwork. Examples of the network according to the embodiment of thepresent disclosure include a wired network such as a LAN or a WAN (widearea network), a wireless network such as a wireless LAN (wireless localarea network), and wireless WAN (wireless wide area network) via a basestation, or the Internet using a communication protocol such as TCP/IP(transmission control protocol/internet protocol) and the like.

The detection apparatus 300 transmits to the image processing apparatus100, for example, the generated parallel X-ray detection data orprojection data in which parallel X-ray detection data has beenconverted.

The image processing apparatus 100 forms an X-ray image based onparallel X-ray detection data by performing the above-describedprocessing performed in the image processing method according to thepresent embodiment, and processing parallel X-ray detection data orprojection data in which parallel X-ray detection data has beenconverted.

Here, the image processing apparatus 100 processes, for example,parallel X-ray detection data transmitted from the detection apparatus300, or projection data transmitted from the detection apparatus 300 inwhich parallel X-ray detection data has been converted. It is noted thatthe image processing apparatus 100 can process, for example, parallelX-ray detection data stored in a storage unit (described below) or thelike, or projection data stored in the storage unit (described below) orthe like in which parallel X-ray detection data has been converted.Examples of parallel X-ray detection data stored in the storage unit(described below) or the like include parallel X-ray detection datagenerated by the detection apparatus 300 and parallel X-ray detectiondata generated by an external device other than the detection apparatus300. Further, examples of projection data stored in the storage unit(described below) or the like in which parallel X-ray detection data hasbeen converted include projection data converted by the detectionapparatus 300 and projection data generated by an external device otherthan the detection apparatus 300.

The image processing system 1000 has, for example, the configurationillustrated in FIG. 9. In the image processing system 1000 illustratedin FIG. 9, the image processing apparatus 100 forms an X-ray image basedon parallel X-ray detection data by performing the above-describedprocessing performed in the image processing method according to thepresent embodiment. Therefore, based on the configuration illustrated inFIG. 9, for example, an image processing system is realized that canachieve a higher quality X-ray image while reducing the calculationcosts for forming an X-ray image even further.

It is noted that the image processing system according to the presentembodiment is not limited to the configuration illustrated in FIG. 9.For example, in the image processing system according to the presentembodiment, the X-ray output apparatus 200 and the detection apparatus300 may be an integrated apparatus, like a CT apparatus that utilizesX-rays or an apparatus having a tomosynthesis function in which X-raysare utilized. Further, if the X-ray output apparatus 200 and thedetection apparatus 300 are an integrated apparatus, such an apparatusmay include a gantry that has a rotary motor, for example.

(II) Example of the Configuration of the Image Processing ApparatusAccording to the Present Embodiment

Next, an example of the configuration of the image processing apparatusaccording to the present embodiment will be described using the imageprocessing apparatus 100 configuring the image processing system 1000illustrated in FIG. 9 as an example.

FIG. 10 is a block diagram illustrating an example of a configuration ofan image processing apparatus 100 according to an embodiment of thepresent disclosure. The image processing apparatus 100 includes, forexample, a communication unit 102 and a control unit 104.

Further, the image processing apparatus 100 may also include, forexample, a ROM (not illustrated), a RAM (not illustrated), a storageunit (not illustrated), a user-operable operation unit (notillustrated), a display unit (not illustrated) that displays variousscreens on a display screen and the like. The image processing apparatus100 connects these constituent elements to each other with a bus thatserves as a data transmission path.

Here, the ROM (not illustrated) stores control data, such as programsand calculation parameters used by the control unit 104. The RAM (notillustrated) temporarily stores programs and the like that are executedby the control unit 104.

The storage unit (not illustrated) is a storage device included in theimage processing apparatus 100, which stores, for example, various datasuch as X-ray detection data, projection data in which X-ray detectiondata has been converted, and applications. Here, examples of the storageunit (not illustrated) include magnetic recording media such as a harddisk, non-volatile memory such as flash memory and the like. Further,the storage unit (not illustrated) may be detachable from the imageprocessing apparatus 100.

In addition, examples of the operation unit (not illustrated) includethe below-described operation input device. Examples of the display unit(not illustrated) may include the below-described display device.

(Hardware Configuration Example of the Image Processing Apparatus 100)

FIG. 11 is an explanatory diagram illustrating an example of a hardwareconfiguration of the image processing apparatus 100 according to anembodiment of the present disclosure. The image processing apparatus 100includes, for example, a MPU 150, a ROM 152, a RAM 154, a recordingmedium 156, an input/output interface 158, an operation input device160, a display device 162, and a communication interface 164. Further,the image processing apparatus 100 connects these constituent elementsto each other with a bus 166 that serves as a data transmission path.

The MPU 150 is configured from, for example, a MPU, various processingcircuits and the like. The MPU 150 functions as the control unit 104 forcontrolling the whole image processing apparatus 100. Further, in theimage processing apparatus 100, the MPU 150 plays the role of, forexample, the below-described processing unit 110.

The ROM 152 stores control data, such as programs and calculationparameters used by the MPU 150. The RAM 154 temporarily stores programsand the like, for example, that are executed by the MPU 150.

The recording medium 156 functions as a storage unit, which stores, forexample, various data such as X-ray detection data, projection data inwhich X-ray detection data has been converted, and applications. Here,examples of the recording medium 156 include magnetic recording mediasuch as a hard disk, non-volatile memory such as flash memory and thelike. Further, the recording medium 156 may be detachable from the imageprocessing apparatus 100.

The input/output interface 158, for example, connects the operationinput device 160 and the display device 162. The operation input device160 functions as an operation unit (not illustrated), and the displaydevice 162 functions as a display unit (not illustrated). Here, examplesof the input/output interface 158 includes a USB terminal, a DVI(digital visual interface) terminal, a HDMI (high-definition multimediainterface) terminal, various processing circuits and the like. Further,the operation input device 160 is, for example, included on the imageprocessing apparatus 100, and is connected with the input/outputinterface 158 in the image processing apparatus 100. Examples of theoperation input device 160 include a button, a direction key, arotating-type selector such as a jog dial, or a combination of these.Further, the display device 162 is, for example, included on the imageprocessing apparatus 100, and is connected with the input/outputinterface 158 in the image processing apparatus 100. Examples of theinput/output interface 158 include a liquid crystal display (LCD), anorganic EL display (organic electroluminescence display, also called anOLED (organic light emitting diode display)) and the like.

It is noted that the input/output interface 158 is obviously alsoconnected to an external device, such as an operation input device(e.g., a keyboard, a mouse etc.) or a display device, as an externaldevice of the image processing apparatus 100. Further, the displaydevice 162 may also be a device that can perform a display and useroperations.

The communication interface 164 is a communication unit included in theimage processing apparatus 100, which functions as the communicationunit 102 for performing wireless/wired communication with the detectionapparatus 300 or an external device, such as a server, via a network (ordirectly). Here, examples of the communication interface 164 include acommunication antenna and an RF circuit (wireless communication), anIEEE 802.15.1 port and a transmitting/receiving circuit (wirelesscommunication), an IEEE 802.11b port and a transmitting/receivingcircuit (wireless communication), or a LAN (local area network) terminaland a transmitting/receiving circuit (wired communication) and the like.

The image processing apparatus 100 performs the processing performed inthe image processing method according to the present embodiment based onthe configuration illustrated in FIG. 11, for example. However, thehardware configuration of the image processing apparatus 100 accordingto the present embodiment is not limited to the configurationillustrated in FIG. 11. For example, if the image processing apparatus100 performs the processing as a standalone configuration, the imageprocessing apparatus 100 may be configured without the communicationdevice 164. In addition, the image processing apparatus 100 may also beconfigured without the operation input device 160 or the display device162.

An example of the configuration of the image processing apparatus 100will be described again with reference to FIG. 10. The communicationunit 102 is a communication unit included in the image processingapparatus 100, which performs wireless/wired communication with thedetection apparatus 300 or an external device, such as a server, via anetwork (or directly). Further, communication by the communication unit102 is controlled by the control unit 104, for example. Here, examplesof the communication unit 102 include a communication antenna and an RF(radio frequency) circuit, a LAN terminal, a transmitting/receivingcircuit and the like. However, the configuration of the communicationunit 102 is not limited to these examples. For example, thecommunication unit 102 may have a configuration that supports anarbitrary standard that is capable of performing communication, such asa USB terminal and a transmitting/receiving circuit, or an arbitraryconfiguration that is capable of communicating with an external devicevia a network.

The control unit 104 is configured from a MPU, for example, which playsthe role of controlling the whole image processing apparatus 100.Further, the control unit 104 which includes, for example, theprocessing unit 110, plays the lead role in the processing performed inthe image processing method according to the present embodiment.

The processing unit 110, which plays the lead role in the processingperformed in the image processing method according to the presentembodiment, forms an X-ray image based on X-ray detection data byprocessing projection data in which parallel X-ray detection data (X-raydetection data representing a detection result of parallel beam X-raysoutput from an X-ray source) has been converted by projection. Morespecifically, the processing unit 110 forms an X-ray image based onX-ray detection data by performing the processing according to theabove-described first example, the processing according to theabove-described second example, or the processing according to theabove-described third example.

Here, for example, if it is possible to directly process the projectiondata in which parallel X-ray detection data has been converted, such aswhen the communication unit 102 has received projection data in whichparallel X-ray detection data has been converted, the processing unit110 process that projection data. Further, for example, in the case ofprocessing the parallel X-ray detection data, such as when thecommunication unit 102 has received parallel X-ray detection data, theprocessing unit 110 converts the parallel X-ray detection data andprocesses the converted projection data. It is noted that the processingunit 110 can also process parallel X-ray detection data stored in astorage unit (described below) or the like, or projection data stored inthe storage unit (described below) or the like in which parallel X-raydetection data has been converted.

The control unit 104 plays the lead role in the processing performed inthe image processing method according to the present embodiment due toits inclusion of the processing unit 110, for example.

The image processing apparatus 100 performs the processing performed inthe image processing method according to the present embodiment based onthe configuration illustrated in FIG. 10, for example.

Therefore, the image processing apparatus 100 can achieve a higherquality X-ray image while reducing the calculation costs for forming anX-ray image even further. Further, the image processing apparatus 100achieves the effects gained from performing the processing according tothe above-described first example when performing the processingaccording to the above-described first example, achieves the effectsgained from performing the processing according to the above-describedsecond example when performing the processing according to theabove-described second example, and achieves the effects gained fromperforming the processing according to the above-described third examplewhen performing the processing according to the above-described thirdexample.

It is noted that the configuration of the image processing apparatusaccording to the present embodiment is not limited to the configurationillustrated in FIG. 10.

(i) First Modified Example

For example, the image processing apparatus according to the presentembodiment may further include a detection unit (not illustrated) havinga similar function and configuration to the detection apparatus 300illustrated in FIG. 9. The detection unit (not illustrated) detectsparallel beam X-rays and generates parallel X-ray detection data, forexample. Further, the detection unit (not illustrated) may also have afunction for, for example, detecting parallel beam X-rays, generatingparallel X-ray detection data, and converting the generated parallelX-ray detection data into projection data by projection.

When the detection unit (not illustrated) detects parallel beam X-raysand generates parallel X-ray detection data, for example, the processingunit 110 converts the X-ray detection data generated by the detectionunit (not illustrated) into projection data by projection, and processesthe converted projection data. Further, in the case of the detectionunit (not illustrated) detecting parallel beam X-rays, generatingparallel X-ray detection data, and converting the generated parallelX-ray detection data into projection data by projection, the processingunit 110 processes the projection data converted by the detection unit(not illustrated). It is noted that the processing unit 110 according tothe first modified example of the present embodiment may also processparallel X-ray detection data stored in a storage unit (describedbelow), or projection data in which parallel X-ray detection data storedin a storage unit (described below) has been converted.

Similar to the image processing apparatus 100 illustrated in FIG. 10,even if it further includes a detection unit (not illustrated), theimage processing apparatus according to the first modified example ofthe present embodiment can perform the processing performed in the imageprocessing method according to the present embodiment. Therefore, theimage processing apparatus according to the first modified example ofthe present embodiment can obtain the same effects as the imageprocessing apparatus 100 illustrated in FIG. 10.

The image processing apparatus according to the present embodiment mayfurther include, in addition to the configuration of the imageprocessing apparatus according to the first modified example of thepresent embodiment, an X-ray output unit (not illustrated) having asimilar function and configuration to the X-ray output apparatus 200illustrated in FIG. 9. The X-ray output unit (not illustrated) has anX-ray source that outputs parallel beam X-rays, for example. Further,the generation of the X-rays in the X-ray output unit (not illustrated)is controlled by the control unit 104, for example.

With the image processing apparatus according to the second modifiedexample of the present embodiment, which in addition to theconfiguration illustrated in FIG. 10, further includes an X-ray outputunit (not illustrated) and a detection unit (not illustrated), thedetection unit (not illustrated) can detect parallel beam X-rays outputfrom the X-ray output unit (not illustrated), for example, and theprocessing unit 110 can process projection data in which parallel X-raydetection data representing a detection result has been converted by thedetection unit (not illustrated). It is noted that the processing unit110 according to the second modified example of the present embodimentcan also process parallel X-ray detection data stored in a storage unit(described below) or the like, or projection data stored in the storageunit (described below) or the like in which parallel X-ray detectiondata has been converted.

Therefore, even with a configuration that additionally includes an X-rayoutput unit (not illustrated) and a detection unit (not illustrated),similar to the image processing apparatus 100 illustrated in FIG. 10,the image processing apparatus according to the second modified exampleof the present embodiment can perform the processing performed in theimage processing method according to the present embodiment. Therefore,the image processing apparatus according to the first modified exampleof the present embodiment can obtain the same effects as the imageprocessing apparatus 100 illustrated in FIG. 10.

(iii) Third Modified Example

When the image processing apparatus according to the present embodimentperforms processing as a standalone configuration, for example, theimage processing apparatus according to the present embodiment may beconfigured without the communication unit 102.

Although an image processing apparatus was described above as anembodiment of the present disclosure, the present embodiment is notlimited to this example. The present embodiment can also be used invarious devices that are capable of processing an image, such as acomputer like a PC (personal computer) or a server, a CT apparatus (anapparatus that uses 360° direction projection data), an apparatus havinga tomosynthesis function (an apparatus that uses projection data of acontrolled angle direction, such as 180° direction projection data), acommunications device such as a smartphone and the like. Further, thepresent embodiment can also be applied in a processing IC (integratedcircuit) that can be incorporated in such devices.

(Program According to the Present Embodiment)

By executing on a computer a program that makes a computer function asthe image processing apparatus according to the present embodiment(e.g., a program capable of executing the processing performed in theimage processing method according to the present embodiment, such as aprogram that makes a computer function as the processing unit 110illustrated in FIG. 10), a higher quality X-ray image can be achievedwhile reducing the calculation costs for forming an X-ray image evenfurther.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

For example, although a program (computer program) that makes a computerfunction as the image processing apparatus according to the presentembodiment was described above, the present embodiment can furtherprovide a recording medium in which this program is stored.

The above-described configuration illustrates one example of the presentembodiment, and naturally comes under the technical scope of anembodiment according to the present disclosure.

Additionally, the present technology may also be configured as below.

-   (1) An image processing apparatus including:

a processing unit configured to processes projection data in which X-raydetection data representing a detection result of parallel beam X-raysoutput from an X-ray source has been converted by projection, and forman X-ray image based on the X-ray detection data.

-   (2) The image processing apparatus according to (1), wherein the    processing unit is configured to divide the projection data and form    the X-ray image per piece of divided projection data.-   (3) The image processing apparatus according to (1), wherein the    processing unit is configured to form the X-ray image each time the    projection data is acquired.-   (4) The image processing apparatus according to any one of (1) to    (3), further including:

a detection unit configured to detect the parallel beam X-rays, generatethe X-ray detection data, and convert the generated X-ray detection datainto the projection data,

wherein the processing unit is configured to process the projection dataconverted by the detection unit.

-   (5) The image processing apparatus according to any one of (1) to    (3), further including:

a detection unit configured to detect the parallel beam X-rays andgenerate the X-ray detection data,

wherein the processing unit is configured to convert the X-ray detectiondata generated by the detection unit into the projection data, andprocess the converted projection data.

-   (6) The image processing apparatus according to (4) or (5), further    including:

an X-ray output unit that includes the X-ray source for outputting theparallel beam X-rays.

-   (7) An image processing method including:

processing projection data in which X-ray detection data representing adetection result of parallel beam X-rays output from an X-ray source hasbeen converted by projection, and forming an X-ray image based on theX-ray detection data.

-   (8) An image processing system including:

an X-ray output apparatus that includes an X-ray source for outputtingparallel beam X-rays;

a detection apparatus configured to detect the parallel beam X-rays,generate X-ray detection data representing a detection result of theparallel beam X-rays, and convert the generated X-ray detection datainto projection data by projection; and

an image processing apparatus that includes a processing unit configuredto process projection data in which the X-ray detection data has beenconverted, and form an X-ray image based on the X-ray detection data.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2012-185292 filed in theJapan Patent Office on Aug. 24, 2012, the entire content of which ishereby incorporated by reference.

What is claimed is:
 1. An image processing apparatus comprising: aprocessing unit configured to process projection data in which X-raydetection data representing a detection result of parallel beam X-raysoutput from an X-ray source through a layer of a target has beenconverted by projection and form an X-ray image from the projection datacorresponding to the layer.
 2. The image processing apparatus accordingto claim 1, wherein the processing unit is configured to divide theprojection data and form the X-ray image per piece of divided projectiondata.
 3. The image processing apparatus according to claim 1, whereinthe processing unit is configured to form the X-ray image each time theprojection data is acquired.
 4. The image processing apparatus accordingto claim 1, further comprising: a detection unit configured to detectthe parallel beam X-rays, generate the X-ray detection data, and convertthe generated X-ray detection data into the projection data byprojection, wherein the processing unit is configured to process theprojection data converted by the detection unit.
 5. The image processingapparatus according to claim 4, further comprising: an X-ray output unitthat includes the X-ray source for outputting the parallel beam X-rays.6. The image processing apparatus according to claim 1, furthercomprising: a detection unit configured to detect the parallel beamX-rays and generate the X-ray detection data, wherein the processingunit is configured to convert the X-ray detection data generated by thedetection unit into the projection data, and process the convertedprojection data.
 7. An image processing method comprising: processingprojection data in which X-ray detection data representing a detectionresult of parallel beam X-rays output from an X-ray source through alayer of a target has been converted by projection and forming an X-rayimage from the projection data corresponding to the layer.
 8. An imageprocessing system comprising: an X-ray output apparatus that includes anX-ray source for outputting parallel beam X-rays; a detection apparatusconfigured to detect the parallel beam X-rays, generate X-ray detectiondata representing a detection result of the parallel beam X-rays througha layer of a target, and convert the generated X-ray detection datacorresponding to the layer into projection data by projection; and animage processing apparatus that includes a processing unit configured toprocess the projection data and form an X-ray image from the projectiondata corresponding to the layer.